To retain control and power over the masses. I mean the Dead Sea Scrolls are a perfect example. The writings were set to challenge a lot of the established religions beliefs in Jesus and his life. They were mysteriously shut down to scholars.

They don't want it to be known that there's alot of info that would of propelled humans to being more advanced, further out in space etc than humans are now. Schools only teach humans to work just enough to feed the system.
Sumerian tablets
Robert Kiyosaki......author of Rich Dad Poor Dad
Aaron Doughty.......Raise Your Consciousness